What is 10VA?

I'm assume by VA you mean Volt-Amperes.

VA is a measurement for "Reactive Power". In simplest of ways you can think of 10 VA as 10 watts. Usually VA is used for Transformers to denote how much electrical energy is being transformed. Sometimes 10 VA of Reactive Power can take 15 or 20 watts to create, But transformers are very efficient nowadays so the 10 VA is either equal to or very close to 10 watts.

I hope I helped!